Processing of synthetic fibers



Feb. 5, 1946.

J. L. GETAZ PROCESSING OF SYNTHETIC FIBERS Filed April 23, 1943 ill! Wmummmuli INVENTR -l Patented Feb. 5, 1946 UNITED STATES PATENT OFFICE PROCESSING OF SYNTHETIC FIBERS James Louis Getaz, New York, N. Y.

Application April 23, 1943, Serial No. 484,221

Claims.

This invention relates to the construction of yarns which are used in the manufacture of te'ir-. tile fabrics. It relates particularly to the construction of synthetic yarns which have some of those properties which are characteristic of W001.

W001 fibers have a protein base known as keratin, and synthetic yarns are now in commercial use which are made of fibers having a protein base and to this extent they more nearly resemble wool than synthetic fibers which are made from a cellulose base. In comparing such synthetic yarns which are made of fibers from a protein base with yarns made from wool, there are two important distinctions which cause the wool to be more desirable.

First, the yarn made from wool is more lofty" while the yarn made from the synthetic fibers in imitation of wool is lean. That is, the yarn made from wool is thicker in diameter than the synthetic yarn of the same weight and has a softer feel. The wool fibers may have a specific gravity which is slightly less than that of the synthetic fibers, but the greater diameter of the wool yarn and its lofty feel is not due to the difierence in specific gravity, but is due to the crimps in the wool. These crimps consist of waves in the shape of the individual wool fibers which are approximately sinusoidal in form. The number of crimps per inch in the wool fibers varies widely with difierent grades of wool. Generally speaking the finer grades of wool in which the fibers are smaller in diameter have the larger number of crimps per inch while the fibers of the low grades of wool which are of comparatively large diameter have very few crimps per inch or may be almost straight.

Yarn made from the fine grades of wool have greater loftiness and warmth because of the larger number of fibers in a yarn of given size made from the fine wool, as compared with the number of fibers in a yarn of the same size made from a coarse wool, and also because the crimps in the fibers of fine wool hold the individual fibers ofthe yarn apart. This holding apart of the fibers by the crimps causes a larger amount of air to be held by the yarn and the low thermal conductivity of the air gives a feeling of Warmth to the yarn.

It is a purpose of this invention to produce a synthetic fiber from which a yarn may be made that has the lofty characteristics of a yarn made from the finest grades of wool.

The second important distinction between W001 and the synthetic fibers made in imitation of wool is due to the peculiar elastic qualities of wool.

This elastic property of wool is in some degree due to the crimps in the individual wool fibers.

When the fibers are stretched the crimps are more or less straightened, and in this straightened condition they have a springlike tension which tends to return to the wave form of the crimped fiber.

It is also a purpose of this invention to produce a synthetic fiber from which a yarn may be made that will have the elastic qualities above mentioned.

Wool fibers are composed of an outer layer of overlapping scales called the epidermis and the inner portion known as the cortex. The structure of the scales of the epidermis causes the wool fibers to have the property of felting, as the scales cause the fibers to move toward their root ends when pressure is applied in the presence of warm soapy water. This property of wool is very valuable in the construction of wool felts or in the fulling of wool fabrics, but this felting or fulling action of the fibers causes a large degree of shrinkage in the fabric, and in fabrics where fulling is not desired this characteristic of wool is a disadvantage, because such wool fabrics may shrink when laundered.

Methods have been tried to prevent this shrinkage of wool fabrics which have not been fulled, but such methods are only efiective when they injure the scales of the epidermis of the wool fibers, and if these scales are injured the durability of the fabrics is reduced.

It is also a purpose of this invention to produce synthetic fibers which will have the lofty and elastic properties of wool but which will not have the characteristic of shrinking when laundered.

To accomplish these purposes mentioned above it is desirable to make yarns of a synthetic fiber with a smooth surface which may be set into a given shape, such as a sinusoidal wave, and

which will resist any force which tends to distort the shape into which it has been set. It is desirable also that this characteristic of resisting distortion of shape should not -be impaired by the processes of handling or by the high temperature used in dyeing or laundering. A synthetic fiber which possesses the desired characteristics for accomplishing these purposes is found in a type of fiber known as "nylon" which is a superpolymer compound made of dibasic acids and diamines, though this invention is not limited to the use of fibers made of this material.

It is an important characteristic of nylon that when it is pressed into a certain shape or form in the presence or moisture at a given temperature that it will tend to resistany force which distorts this shape after the pressure is removed and the temperature is lowered. On account of this property of nylon, ii nylon fibers are pressed into a certain shapein the presence moisture at a temperature of 240" F., held at this temperature long enough for the shape to set and cooled while still held in the desired shape, these fibers will retain this shape even though they are dyed or laundered in a boiling bath oi 212? F.

The preferred methods of processing the nylon fibers to accomplish the purposes of this invention are shown in the following drawing and description:

Fig. 1 shows a nylon fiber which has been set with a crimp which is similar to the crimp in wool'fibers.

Fig. 2 shows an elevation of a machine for putting such a crimp in synthetic fibers under the combined effect or steam and heat applied from another source.

Fig. 3 is a plan view of the machine shown in Figure 2.

After the nylon fibers have been manufactured from the liquid state and stretched the desired amount they may be processed in accordance with my invention.

The machine shown in Figures 2 and 3 is designed to process the fibers in a continuous operation, the fibers 20 being fed between two endless beds 50 and 5|. As these fibers 20 are fed between the beds 50 and El, they are placed parallel to each other and lie in the direction of the line of travel as shown in Fig. 3. Across the face of these beds are corrugations which press the crimps in fibers 20 to the waveshape shown in Figure 1. These beds turn on wheels 52, which are driven by motor 53, and in so doing draw fibers from cone 54 and as they are delivered at the other end of these beds, these fibers are wound on spool 55. The beds 50 and 5| are heated where they are in contact with each other at the receiving end of the fibers by steam which is admitted through pipes 56 and which comes in contact with the fibers through holes 51 in the beds. Toward the delivery end of the fibers the beds 50 and 5| are cooled by compressed air which is admitted through pipes 56', so that the fibers 26 are cool before they are delivered by the bed 50 and 5| to the spool 55. The speed of-travel or the beds 50 and 5| is so timed that the time in which the fibers 2|! are in contact with the steam from pipes 56 is sufiicient to cause the corrugations to be set in the fiber, and the distance covered b the compressed air from pipes 58 is sufficient to cool the beds before the fibers are delivered. If the steam is saturated and at atmospheric pressure when it comes in contact with the fibers 20, it cannot heat them above 212 F. Ii it is desired to process the fibers at a higher temperature so that they will hold their shape it boiled in dyeing or laundering, this higher temperature may be obtained by superheating the steam. II the steam is discharged from orifices in pipes 56 at relatively high pressure it will become superheated as it is discharged into atmospheric pressure, or it may be superheated in the customary manner by generating superheated steam in a boiler.

A method of raising the temperature of the fibers above the temperature or the steam while they are being processed is shown in Figures 2 and 3. The portion of beds 50 and 5| contain rheostats 61 connected to electrodes 68. After the portions oi bed '50 are cooled by thecompressed air from pipes 58, the electrodes 68 come in contact with rails 59 and 60 which are connected to an electric circuit through leads 6| and 62. As the portions of bed 50 travel back to the feeding point of fibers 20, they are heated by the electric current and this heating action of the current continues while the portions oi the bed are passing between the steam pipes 56 until they reach the ends of rails 59 and 50. In a similar manner the portions of bed 5| are heated in contact with rails 63 and a corresponding rail on the other side of the machine which is not shown, which are connected to an electric circuit through leads 65 and 66.

The processes mentioned above are designed to set the shape of the fibers in the form of a wave similar to the crimp in wool fibers, so that when these fibers are spun into a yarn, the fibers of the yarn will be held apart by the crimps in each individual fiber, with the result that the yarn will be lofty."

To accomplish the purpose of this invention, in its most desirable form, it is important that the fibers retain their crimped form .permanently after processing is completed. To obtain this permanence of shape there are' two features which are essential. The first of these is that the fibers be held rigidly in the crimped shape in the presence oi moisture and at the proper temperature for a sufiicient length of time to allow the crimped shape of thefibers to become set, and this time may vary from a few minutes to an hour depending on conditions and the character of the fiber. The second feature is that after these fibers are properly treated for sufilcient length of time, that they must be brought to a lower temperature before any tension is applied to them. If tension sufiicient for winding is applied to these fibers after they are set but before their temperature is reduced, the effect of this tension, however slight, is to flatten the crimps in the fibers, and this flattening of-the crimps destroys the'lofty efi'ect in the yarn and finished fabric which may be made from these fibers.

I claim:

-l. A process of continuously forming permanent crimps in arallel filaments of synthetic fibers, similar to the crimps in the better grades of wool, which comprises continuously feeding said filaments between cooperating forms in parallel relation and in position to form said crimps, continuously moving said forms through a space to which steam and additional heat is applied for a definite length of time sufficient to heat said filaments and maintain them at an elevated temperature to set said crimped shape in said filaments, continuously moving said forms containing said filaments through a space in which a cooling agent is applied for a definite length of time sufiicient to cool said filaments, said relative position of said forms and said filaments remaining unchanged during said time in which said filaments are heated and maintained at an elevated temperature and are subsequently cooled, and discharging said filaments from said forms.

2. A process of continuously forming permanent crimps in parallel filaments of synthetic fibers, which comprises continuously feeding said filaments in parallel relation between two endless series of continuously moving cooperating crimping forms, bringing opposed forms together to crimp said filaments while maintaining their parallel relation, continuously moving said forms with the parallel filaments therebetween along an extended path while maintaining the relative position of said forms to hold said parallel filaments in crimped position, applying heat to said filaments and holding them at elevated temperature during a portion of said path of travel of said forms to set said crimped shape in said filaments, applying a cooling medium to said filaments during another portion of said path of travel of said forms to cool said filaments while still maintaining the relative positions of said forms, and thereafter discharging said filaments from said forms.

3. A process of continuously forming permanent crimps in parallel filaments of synthetic fibers, which comprises continuously feeding said filaments in parallel relation between two endless series of continuously moving cooperating crimping forms, bringing opposed forms together to crimp said filaments uniformly while maintaining their parallel relation, continuously moving said forms with the parallel filaments therebetween along an extended path while maintaining the relative position of said forms to hold said parallel filaments in crimped position, subjecting said filaments to the direct action of steam to heat said filaments, holding said filaments at elevated temperature during a portion of said path of travel of said forms to set said crimped shape in said filaments, thereafter subjecting said filaments to the action of a cooling agent during another portion of said path of travel of said forms to cool said filaments while still maintaining the relative positions of said forms, and thereafter discharging said filaments from said forms.

4. A process of continuously forming permanent crimps in parallel filaments of synthetic fibers, which comprises continuously feeding said filaments in parallel relation between two endless series of continuously moving cooperating crimping forms, bringing opposed forms together to crimp said filaments uniformly while maintaining their parallel relation, continuously moving said forms with the parallel filaments therebetween along an extended path while maintaining the relative position of said forms to hold said parallel filaments in crimped position, subjecting said filaments to the direct action of steam and applying additional heat to 5. A process of continuously forming permanent crimps in parallel filaments of synthetic fibers, which comprises continuously feeding said filaments in parallel relation between two endless series of continuousl moving cooperating crimping forms, bringing opposed forms together to crimp said filaments uniformly while maintaining their parallel relation, continuously moving said forms with the parallel filaments therebetween along an extended path while maintaining the relative position of said forms to hold said parallel filaments in crimped position, applying heat to said filaments in the presence of moisture to raise the temperature of said filaments to a temperature not less than 212 F. and holding them at elevated temperature during a portion of the path of travel of said forms to set said crimped shape in said filaments, subjecting said filaments to the action of a cooling agent during a subsequent portion of said path of travel of said forms to cool said filaments while still maintaining the relative positions of said forms, and thereafter discharging said filaments from said forms.

JAMES LOUIS GE'I'AZ. 

